The paper bag as the first stage of filtration, and provides a clean form of disposal of the collected dust. From a 2-ply pulp material, the 1.3 liter bag capacity offers an extra large surface area, loss of suction to the bag starts to fill. A package of five paper bags are standard with a vacuum cleaner. The paper should be replaced as needed, so it depends on the frequency of the vacuum and the nature of the material again. The paper bag retains 99.7% of all particulates to 3 microns in size.